1. Field of the Invention
This invention relates to semiconductor device packages and more specifically, relates to semiconductor device packages having substrates that redistribute the electrodes of the semiconductor devices housed therein.
2. Description of the Art
III-nitride based power semiconductor devices, such as Gallium Nitride (GaN) based devices, are desirable for power applications. Example III-nitride based devices include diodes, unidirectional switches, and bi-directional switches. These devices are lateral conductive devices with the power electrodes and control electrodes disposed along a top surface of the devices and with the bottom surface of the devices being electrically non-conductive.
Referring to FIG. 1 there is illustrated an example III-nitride based power device 121. Device 121 is a unidirectional switch that includes a control/gate electrode 122 and first and second power electrodes 123 and 124, one power electrode being the source electrode and the other power electrode being the drain electrode. As shown, the two power electrodes are interdigited and may include elongated runners 123a and 124a that extend along respective edges of device 121. Notably, if device 121 were a bi-directional switching device, power electrodes 123 and 124 would both be source electrodes and the device may further include a second control/gate electrode. A III-nitride based bi-directional switching device may have a form as disclosed in U.S. Publication No. US 2005-0189561 (U.S. patent application Ser. No. 11/056,062), entitled “III-Nitride Bidirectional Switch,” by Daniel M. Kinzer et al., and assigned to the assignee of the present application. The contents of U.S. Publication No. US 2005-0189561 are hereby incorporated by reference as if fully set forth in its entirety herein. Similarly, if device 121 were a diode, the device would only include power electrodes 123 and 124. When packaging a device such as device 121, wire bonds may be formed from a contact pad of control/gate electrode 122 and from elongated runners 123a and 124a to the terminal leads of the device package to connect the terminal leads to the device electrodes.
Notably, a III-nitride based power semiconductor device may have a very small area, thereby making the electrodes of the device also very small. The small size of these electrodes can create substantial problems when interfacing to the electrodes. For example, as indicated above a III-nitride based device may be mounted within a device package that has one or more terminal leads, with wire bonds being formed directly between the terminal leads and device electrodes. Notably, the small size of the electrodes can make it difficult to form these wire bonds. Similarly, small electrodes often prohibit the direct mounting of devices to an end customer's circuit board. This is due to the spacing between the electrodes on the III-nitride based devices being significantly less than the spaces achievable using printed circuit board patterning processes.
In addition to III-nitride based devices, lateral conductive silicon-based power devices may also have very small areas, thereby again resulting in electrodes of a very small size. Accordingly, such devices may also exhibit similar problems as described above.